Vacuum feeder for plywood veneer core sheets



United States Patent [111 3,533,518

[72] Inventor Harold .-\.Keller [56] References Cited Lewismm UNITEDSTATES PATENTS QY J' i zfg 3.391.926 7/l968 .Iuutinen ..214/8.5(D)UX x969 K ll .214 8.5 DlUX 451 Patented on. 13 1970 3463'483 H I [73]Assignee Potlatch Forestglnc, PrimaryExaminer-Gerald M.ForlenzuLewiston, Idaho Asxislam E.\'aminerGeorge F. Abraham a corporation ofDela Al!0rI1e Wells and St. John VACUUM FEEDER FOR PLYWOOD VENEERABSTRACT: A vacuum teeder 15 described for SUCCfiSSlVCl) removingplywood core sheets from a stack and aligning the g'gff gg Sheets andfeeding the Sheets crosswise forward to u plywood d m layup Station. Thefeeder includes a first hood that moves [52] US. Cl 214/85. down toreceive the top Sheet of the stack and then moves up- 27l/l4 ward toremove the sheet from the Stack. The first hood iS [5 l Int. Cl 365g59/04 Shifted transversely to align one end edge of the Sheet before[50] Field ofSearch 2l4/8.5(A). conveying the Sheet to a Second vacuumhood that moves the 8.5(D),8.5: 271/14. 28 Sheet forward.

Patented Oct. 13, 1970 Sheet INVENTOR. Hana/d 14. lfEl/E'R mm li. $0M

07 rys.

Patented Oct. 13, 1970 3,533,51

Sheet 2 014 1N VENTOR.

HnRo/d H. Kai/5R BY mm. (5 1&3.

Hrrys.

Patented Oct. 13, 1970 3533,51

Sheet 3 of 4 IN VENTOR.

Patented Oct 13, 1970 Sheet 4 014 INVENTOR. HnRo/d H. KEl/ER BY flrrys.

VACUUM FEEDER FOR PLYWOOD VENEER CORE SHEETS BACKGROUND OF THE INVENTIONThis invention relates to equipment for handling veneer sheets and moreparticularly to vacuum feeders for feeding core sheets to a plywoodlayup station.

This is a companion application to a copending U.S. patent applicationSer. No. 814,581, filed Apr. 9, 1969, Method and Apparatus forAutomatically Laying Up Plywood Panels."

Plywood core material is generally referred to as material placedbetween the face veneer sheets in the formation of plywood panels.Generally the core material is of low grade quality having cracks,knots, knotholes and other defects therein. Core crossband sheets arethose sheets having the wood grain running perpendicular to the lengthsof the sheets. Often the crossband sheets are constructed from severalsmaller individual pieces four feet in length that are placed side byside to form a sheet having a length of eight feet. String, tape or edgegluing is sometimes used to hold the individual pieces together to forman integrated sheet.

It is very difficult to handle formed crossband sheets especially toseparate the sheets in a stack and rapidly convey the sheets withoutdamaging or breaking the sheets. One of the principal reasons why it hasbeen difficult to develop automatic plywood layup equipment is theinability to effectively and efficiently machine handle the crossbandsheet.

One of the principal objects of this invention is to provide a veneersheet feeder that is reliable and efficient for successively picking upplywood core sheets from a stack and accurately conveying the sheets tolayup station like the one disclosed in said companion application.

An additional object of this invention is to provide a vacuum feedercapable of removing the low grade veneer sheets from a stack andconveying the sheets to a layup station at a relatively fast speedwithout damaging the core sheets.

A further object of this invention is to provide a vacuum sheet feederthat is capable of squaring and centering the core sheets as they arebeing fed to the layup station.

An additional object of this invention is to provide a vacuum feederthat utilizes the directional strength properties of the cores sheets toprovide a simple and efficient conveying means.

These and other objects and advantages of this invention will becomeapparent upon the reading of the following detailed description of thepreferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of thisinvention is illustrated in the accompanying drawings, in which:

FIG. I is a side elevational view of the vacuum feeder for successivelypicking up core veneer sheets from a stack and conveying the sheets to alayup station;

FIG. 2 is a fragmentary plan view of the vacuum feeder;

FIG. 3 is a vertical cross-sectional view taken along line 3-3 in FIG.2;

FIG. 4 is a fragmentary detail cross-sectional view taken along line 44in FIG. 2 showing the top sheet of the stack being moved upwardly fromthe stack;

FIG. 5 is a fragmentary detailed view similar to FIG. ,4 only showingthe sheet shifted transversely to align one end of the sheet; and I FIG.6 is a vertical cross-sectional view taken along line 6-6 in FIG. 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring now in detailto the drawings, there is shown in FIG. 1 a core sheet feeder 10 forsuccessively picking up core veneer sheets 11 from a stack 12 andconveying the sheets to a downstream layup station. The stack of coreveneer sheets is fed to the feeder on a roll case 13.

The core sheet feeder has a support frame 14 with spaced end uprightframe members 16 and 17 (FIGS. 2 and 3) at one end thereof. Plate steelguides 18 and 20 are mounted on the upright members 16 and 17respectively for roughly centering the core stacks I2 crosswise to thefeeder I0 and to the direction of travel of the sheets. The spacingbetween the guides 18 and 20 is slightly greater than the length of thesheets so as the stacks are moved between the guides 18 and 20 thestacks are roughly aligned with the core sheet feeders.

A conventional hydraulically operated scissor life 32 is mounted at theend of the roll case 13 for successively receiving the individual stacksl2 beneath the vacuum hood assembly and for maintaining the height ofthe stack at a susbstantially constant elevation with respect to thenormal position of the vacuum hood assembly 25. An upright stack stop 33is mounted adjacent and alongside the scissor lift 33 to stop themovement of the stack as the stack moves from the roll case onto thescissor lift. A brace 34 is connected between the floor and the uprightstop 33 for maintaining the stop in a substantially vertical position toprevent a stack from moving the stop 33. Electric eye elements 35 and 36(FIGS. 1 and 2 are mounted on the end upright frame members 16 and I7respectively and are directed in a substantial horizontal direction forsensing when the height of the scissor is below the eye elements. Theeye elements control the scissor lift to maintain the height of thestack at a prescribed elevation. The scissor lift is lowered by theoperator.

The main support frame 14 also includes support columns 22 and 23 at theother end of the feeder for supporting a vacuum hood assembly 25elevated from the floor above the height of the stack. The vacuum hoodassembly 25 includes a substantial horizontal frame 26 that is pivotallymounted to the columns 22 and 23 through pivot bearings 27. The frame 26includes side frame members 28 and 29 (FIG. 2) that extend parallel tothe direction in which the sheets are to be fed and cross members 20a,30b and 300 that interconnect the side members to provide asubstantially rigid support for the vacuum hood assembly 25.

Acutators 3] are mounted on the frame members 16 and 17 and connected toone end of the frame 26 for raising and lowering the vacuum hoodassembly to pickup and remove the top sheet of the stack.

The vacuum hood assembly 25 includes a first vacuum hood 38 that ismovably mounted on the frame 26 for transverse movement in a horizontaldirection for shifting the veneer sheets endwise to align one end of thesheet along a selected plane Y (FIGS. 4 and 5) that is parallel to thedirection in which the sheets are fed to the layup station. The firstvacuum hood 38 is mounted to the frame 26 immediately above the scissorlift 32. A second vacuum hood 40 is stationarily mountedto the pivotframe 26 adjacent the hood 38 to receive the sheets from the firstvacuum head and convey the sheets thereunder in the direction to thelayup station. Each of the vacuum hoods 38 and 40 have large bottomdownwardly directed openings 41 and 42 (FIG. 6) respectively fordirecting vacuum pressure therethrough to hold the sheets to theunderside of the vacuum hood assembly.

Spaced plenum chambers 43 and 44 are mounted on the first vacuum hood 38for directing vacuum pressure into the hood 40. Spaced plenum chambers45 and 46 are mounted on the first vacuum hood 38 for directing vacuumpressure into the first vacuum hood. A common vacuum duct 47interconnects the plenum chambers 43-46 to a vacuum source. The vacuumduct may be directly tied to a vacuum fan or may be connected to acommon vacuum system located in a plywood plant.

The first vacuum head 38 is slidably mounted on guide rods 50 and 51 theextend between the side members 28 and 29 above the scissor lift 32. Thevacuum head 38 has bearings 52 and 53 mounted thereon that fit on theguide rods 50 and 51 respectively. A fluid pressure actuator 54 (FIG. 2)is mounted on the side frame 28 parallel with the rods 50 and 51 and isconnected to the first vacuum frame 38 for moving the frame back andforth along the rods 50 and 51 to shift the core sheets received by thevacuum hood 38 to align one end with the reference plane.

The first vacuum hood 38 includes a conveying means mounted within thelarge opening 41 for conveying the sheet from the first vacuum head tothe second vacuum head underneath the first vacuum head after the sheethas been removed from the stack. The conveying means includes a plurality of rollers 56 that are mounted in the opening 41 transversely tothe grain of the sheets to move the sheets forward in a directionparallel to the grain of the sheets. The individual rollers areidentified by 56a, 56b, 56c and 56d. The ends of the rollers extendthrough the sides of the vacuum head and are rotatably mounted inbearings 57. Pulleys 58 are mounted on the end of the rollers and areconnected by common belts 59. A motor 60 (FIG. 2) is connected to thebelts for rotating the rollers 56 when the vacuum hood assembly israised to the up position to move the sheet received thereby from thefirst vacuum hood 38 to the second vacuum hood 40. Elongated transverseseals 61 (FIG. 6) are mounted between the top of the vacuum hood 38 toslidably engage the rollers to divide the interior of the vacuum hoodinto vacuum compartments 62 between the rollers. The individual vacuumcompartments are identified as 62a, 62b, and 62s.

Orifice apertures 63 are formed between the hood 38 and the plenumchambers 46 to regulate the flow and pressure of the vacuum pressure inthe hood.

Relief valves 65, 66 and 67 (FIG. 2) are mounted in the top of the hood38 communicating with the compartments 62a, 62b and 620 respectively toprevent pressure in the hood from increasing above a preset vacuumpressure. It has been found that this feeder works exceedingly well whenthe relief valves are set to open at 0.55 inches of water static vacuumpressure.

Side slots 69 and 70 (FIG. I) are formed in the side of the vacuum hood38 communicating with the vacuum compartments 62b and 62c.

Sensing means are mounted on the side frame member 26 in transversealignment with the slots 60, 70 for sensing when the one end of thesheet has been shifted sufficiently to align the end edge with theprescribed plane. The sensing means are mounted on a bracket 72 (FIGS.I, 2, 4 and that is fixed to the side member 28. Individual U-shapedbrackets 74 and 75 are mounted on the bracket 72 in transverse alignmentwith the slots 69 and 70. Electric eye elements '76 and '77 (FIGS. 4, 5)are mounted on the bracket 7 and 75 in vertical alignment with thevertical plane for sensing when the end edge of the sheet has beenaligned.

The electric eye elements 76 and 77 are operatively connected to theactuator 54- to stop the transverse movement of the vacuum hood 38 whenthe edge of the plywood sheet is aligned along the vertical plane Y.

In operation the actuators 31 move the hood 38 down against the topsheet on the stack. The hood 38 is then raised. As the hood moves up theactuator 54 is operated to shift the hood as shown in FIG. 4 and 5 toalign one end edge in the vertical plane Y. When the light is broken theactuator is stopped and the motor 60 is operated to convey the alignedsheet forward to the second hood 40.

The second vacuum hood 40 also includes a conveying means for moving theplywood along the bottom thereof. The conveying means includes aplurality of rollers 80 (FIG. 6) that are mounted in the large downwarddirected opening 42 transverse to the grain d, the sheets and directionof feed for receiving the sheets of plywood fed from the first vacuumhood 38. The rollers are idividually identified as 80a, 80b, 80c, 80d,80c and 80f. The end of the rollers extend through the side of the hoodand are rotatably mounted in bearings 81 (FIG. 1). Small diameterpulleys 82 are mounted on the ends of the rollers80a, 80b and 80c andlarge diameter pulleys 83 are mounted on the ends of the rollers 80a,80c and 80f. The pulleys 82 and 83 are interconnected by belts 84 thatare driven from a common motor 85. The motor 85 is continually operatedto maintain the rollers 80 in constant motion.

Because of the diameter ratio between the large pulleys 83 and thesmaller pulleys 82, the rollers d, 80e and 80frotate at a slower ratethan the rollers 80a, 80b and 800. The rollers 56 and the rollers 80a,80b, 806 are rotated at the same rate to move the core sheets crosswaysin the direction of feed at a fast speed and then the rate of feed isslowed as the sheets approach the forward end of the feeder. In one unitthe beginning rate is approximately 300 feet per minute and then therollers 80c, 80d and 806 slow the movement down to a rate ofapproximately I00 feet per minute.

The conveying means for the second vacuum hood 40 moves the leading edge(side edge) into a horizontal elongated stop 88 (FIG. 6) for accuratelyaligning the leading edge perpendicular to the movement of the sheet.Stop 88 is connected to an intermittent drive means 90 (FIG. 1) thatmoves the stop out of the way at precise intervals in coordination withthe layup process at a downstream layup station. From the stop 88 thesheets move to a drive roller 91 (FIG. 6) that is rotated by a motor 92(FIG. 1). A biasing or nip roller 93 is mounted immediately above thedrive roller for biasing the sheet firmly against the drive roller totransmit the rotation of the drive roller to the sheets to convey thesheets at a prescribed rate to the downstream layup station. An exampleof such a downstream layup station is described in the companionapplication previously mentioned.

The vacuum source is a low pressure, high volume source. It has beenfound that for low grade core sheets a static vacuum pressure in thehood 38 of between 0.5 and 3.0 inches of water is sufficient to pick offthe top sheet from the stack without picking up the second sheet.

I claim:

I. In plywood layup equipment, a core sheet feeder for successivelyremoving core sheets from a stack and moving the sheets crosswise in ahorizontal direction with one end edge of the sheets aligned in avertical reference plane parallel with the horizontal direction, saidcore sheet feeder comprising:

a. a frame positioned along the horizontal direction;

b. a vacuum hood mounted on the frame overlying the core stack forvertical movement and for shifting transversely to the horizontaldirection, said hood having an underside downward directed openingtherein;

a source of vacuum pressure directed downward through the opening tohold the sheet to the underside of the hood;

d. a first drive means mounted on the frame for moving the hood down tothe stack to receive the top sheet of the stack on the underside of thehood, for moving the hood upward to remove the received sheet from thestack and position the sheet crosswise to the horizontal direction;

a second drive means mounted on the frame for shifting the hoodtransversly to the horizontal direction to shift the sheet endwise',

. control means operatively connected to the second drive means forcontrolling the second drive means to align one end edge of the sheet insaid reference plane; and

g. a conveying means mounted on the hood that is responsive to thealignment of the end edge of the sheet for moving the sheet beneath thehood in the horizontal direction.

2. A core sheet feeder as defined in claim 1 wherein said conveyingmeans includes a plurality of spaced rollers mounted in the undersideopening transversely to the horizontal direction for receiving thesheets and moving the sheets beneath the hood in the horizontaldirection.

3. A core sheet feeder as described in claim 1 wherein the control meansincludes one or more electric eye sensing devices mounted on the framefor sensing the alignment of the end edge in the reference plane,

4. A core sheet feeder as defined in claim 1 wherein the second drivemeans is operated in cooperation with the first drive means to align theend edge as the vacuum hood is moved upward.

5. A core sheet feeder as defined in claim 1 further comprising a secondvacuum hood horizontally stationarily mounted on the frame for receivingthe sheets from the first vacuum hood and wherein the second vacuum hoodhas a conveying means mounted thereon for moving the sheets forward inthe horizontal direction.

6. A core sheet feeder as defined in claim 5 wherein the conveying meansof the second vacuum hood includes a plurality of spaced rollersrotatably mounted to the second hood transversely to the horizontaldirection and a motor means connected to the rollers for rotating therollers to move the sheets beneath the hood in the horizontal direction.

7. A core sheet feeder as defined in claim 5 further comprising areleasable stop means mounted on the frame transversely to thehorizontal direction for stopping the forward movement of the sheetsbeneath the second vacuum hood and for releas ing the sheets atintermittent intervals to permit the continued forward movement ofthesheets.

8- In plywood layup equipment, a vacuum feeder for succes sivelyremoving core veneer sheets from a stack and moving the sheets crosswisein a horizontal direction parallel with the grain of the core veneersheets, said vacuum feeder comprising:

a. a frame positioned along the horizontal direction;

b. a vacuum hood assembly mounted on the frame with a first vacuum hoodoverlying the stack and an adjacent second vacuum hood extending in thehorizontal direction; each of said hoods having underside downwardopenings therein, said first vacuum hood being movably mounted forvertical movement and for shifting transversely to the horizontaldirection;

c. a first set of spaced conveying rollers rotatably mounted in theopening of the first vacuum hood transversely to the horizontaldirection;

a second set of spaced conveying rollers rotatably mounted in theopening of the second vacuum hood transversely to the horizontaldirection;

a source of vacuum pressure connected to the first and second vacuumhoods for directing vacuum pressure downward through the openings tohold the core veneer sheets against the conveying rollers;

a first drive means mounted on the frame for moving the first vacuumhood down to the stack to receive the top core veneer sheet and formoving the first vacuum hood upward to move the received sheet from thestack;

a second drive means mounted on the frame for shifting the first vacuumhood transversely to the horizontal direction to move the received sheettransversely;

. an edge sensing device mounted on the frame and operatively connectedto the second drive means for stopping the transverse shifting of thereceived sheet when one end edge of the sheet reaches a preset verticalreference plane;

. a third drive means mounted on the frame operatively connected to thefirst set of rollers for rotating said rollers to move the sheet in thehorizontal direction from the first vacuum hood to the second vacuumhood; and

. a fourth drive means mounted on the frame and operatively connected tothe second set of conveying rollers for rotating said rollers to movethe sheet in the horizontal direction beneath the second hood.

